"....yes, the kids had low risk, but not zero..." It was statistically zero relative to cases. To pretend otherwise is as dishonest as most of what you say. The risk to kids was lower than about a billion other "risks" they would encounter in their normal school attendance annually.
"I you were a 50+ Grade School teacher in that time, place, environment, I doubt you'd be so sanguine about opening up." There were plenty of mitigations to easily cover this. Older instructors could have done so remotely to an attending class of kids in the room, if they wished not to teach in person. Keeping kids remote while unions held the kids/families hostage in attempt to extort unrelated benefits was unforgivable.
Shutting down for 2 weeks made sense. We were essentially all okay with the 15-days plan (which turned out to be a blatant lie to the American people). The argument for a month longer could be swallowed, as long as it was clear what necessary infrastructure needed to be put in place for the teachers who refused to come in or kids whose parents wanted them learning virtually.
But we had plenty of information that this would work just fine, and every idiot who supports the shutdowns that extended beyond the summer is an embarrassment.